Toy building block



FIG. 1 is a front perspective view of a toy building block showing my new design;

FIG. 2 is a rear perspective view thereof;

FIG. 3 is a rear elevational view thereof;

FIG. 4 is a side elevational view thereof, the side opposite being a mirror image,

FIG. 5 is a front elevational view thereof; and

FIG. 6 is a bottom plan view thereof. 

The ornamental design for a toy building block, as shown and described. 